Pressure relief valves, i.e., valves which make possible the switching of the pressure in a hydraulic system between an operating pressure and a lower circulation pressure, are known in numerous variations, in particular also in the form of combined pressure release and pressure control valves (see, for example, the pamphlet D-6.4 "Electrically actuated pressure control and pressure reducing cartridges NG10" by the company Hydrotechnik Frutigen AG, Apr. 30, 1998 [sic]). These known valves are provided with a main valve with a relatively strong resetting prestress that acts in the closing direction so as to prevent malfunctions, in particular at higher operating pressures as well as higher flow rates. However, this high closing or resetting prestress causes a correspondingly high circulation pressure in the unloaded condition of the valve, whereby the aforementioned circulation pressure of these known valves lies between approximately 4 and 8 bar.